The present invention relates to a method for drying hollow bodies having an access opening, especially for drying industrial barrels after washing, where the hollow body is tilted and a residual liquid quantity that is still contained in the hollow body and that has gathered at a lowest point of the hollow body is removed from the hollow body by means of a suction pipe introduced through the access opening.
The invention further relates to an apparatus for drying hollow bodies having an access opening and being positioned on an inclined support, especially for drying industrial barrels after washing, having holding means for the hollow bodies and a suction pipe as well as a displacing device for introducing the suction pipe into the access opening in such a way that the end of the suction pipe comes to lie at the lowest point within the hollow body.
A method and an apparatus of the before-mentioned type is known from SU-PS-423 530.
Given the general shortage of raw materials, it is of general interest, with respect to the use of hollow bodies, to enable even such hollow bodies, which formerly would be used only once, i.e. as a single-used packing, to be used repeatedly, i.e. as a multiple-use packing.
Whenever the term "hollow bodies" is used in the context of this application, this term is to be interpreted as referring to industrially employed containers by means of which liquids or pourable solid materials are transported. For reasons of greater simplicity and better illustration, the following specification will refer to the example of industrial barrels, without however thereby limiting the scope of the present invention.
Industrial barrels are produced and in use in different sizes and different designs. One typical industrial barrel is a steel-sheet drum having a diameter of approximately 560 mm and a height of approximately 900 mm, corresponding to a volume of approximately 220 liters. Barrels of this type are used for transporting the most different goods, including for example organic liquids, such as oils, varnishes, fuels, and the like.
Such industrial barrels are already in use as multiple-use packings, which requires however that the barrels be reconditioned after every use. According to the known reconditioning methods for such barrels, one proceeds for example as follows: First of all, any residual content is removed from the barrels. Then the barrel inside is washed, for example using a soda lye, and then rinsed. The barrel edges are then mechanically dressed, and dents are removed from the barrel bodies, for example by blowing in compressed air. Thereafter, one removes old external paint finishes, if any, and cleans the barrel from rust. Finally, a new paint finish is applied, the barrels are checked for tightness, rinsed once more with water, and are then dried.
It is of course desirable that upon completion of these procedural steps, the barrel inside should be dry, if possible. This is necessary on the one hand in order to prevent further corrosion of the barrels; on the other hand, however, it must be ensured that no residual liquid or residual water remains in the barrel as such residual quantities could possibly react with the medium to be filled in later.
According to the known methods, final drying of the barrels was effected by heating them directly with a gas flame, or by drying them with hot air, hot steam and compressed-air. In a practical example, for drying a barrel of the described type, 5 Kg of steam at a pressure of 12 bar are needed for example, in which case a circulating-air temperature of 180.degree. C. can be reached via a heat exchanger. For pre-heating the barrels, 0.05 Kg of fuel oil and a total of approximately 0.2 KW of electric power are consumed per barrel for the circulating-air fans and the blow-out devices.
In drying barrels of this type, it has further been known to heat compressed-air via heat exchangers and to blow the heated air into the barrels, but this process that does without recirculated air leads to an even higher energy consumption.
All these known methods have in common that they require not only a high energy input for drying a barrel, but that in addition it cannot be excluded, for none of the before-mentioned methods, that the barrel still contains a residual quantity of humidity, in particular a residual water quantity, especially when hot steam is used for drying and when the residual heat of the barrels is to be utilized for final drying.
SU-PS-423 530 describes a barrel-washing machine by means of which the barrels are washed and then dried in a position in which the barrels are tilted. Any residual liquid left in the barrels is drawn off at the lowest point of the inner space of the barrels by means of a suction pipe. In the case of the known machine, this is done in an upside down position, which means that the barrels are mounted on the suction pipe with the access opening in downward position. A thin tube, which is then swung out laterally from the suction pipe, reaches down to the lowest point of the hollow interior of the barrel.
The known machine does not have any means for seating the barrels. Although the known machine comprises a pipe section suited for extracting air and steam from the machine, this pipe section only has the function of a chimney because the machine is freely accessible from the side. This is so because big openings can be seen in the sidewalls of the machine, with a frame extending through these openings for introducing barrels into, and removing them from, the interior of the machine. These openings are suitably sized to permit the machine to be loaded from one side and to be discharged on the opposite side.
Thus, the known machine offers the disadvantage that "drying" is possible, if at all, only insofar as the liquid flows off the barrel spontaneously, through the access opening pointing to the bottom, or is extracted by means of the suction pipe that has been introduced from below and has been swung out laterally. Beyond this, a drying action is neither envisaged, nor possible.
DE-OS 23 55 910 describes another method for drying containers. According to this known method, a probe designed in the form of a flame thrower is introduced into the container, and a fuel gas, such as butane, propane of natural gas, is guided through the probe and ignited so that the container inside is dried by the resulting flame.
It is understood that, therefore, this known method can be used only for certain specific containers that will not change inadmissibly by the direct contact with the flame. In addition, the generation and handling of flames as part of an industrial production process is problematic also under safety aspects.